Organic matrix composite (OMC) structures, and in particular high temperature OMCs, are finding increased applications on products such as split fan bypass ducts. Repair of mis-machined holes or small local surface damage can be expensive and complicated. A tapered composite plug is bonded inside the tapered hole that has been prepared in the duct with the use of a thermoset adhesive that requires heat and pressure for consolidation and cure. In some cases, heat and pressure are applied through the construction of a vacuum bag around the repair followed by processing in a heated, pressurized autoclave.
Current practices for adhesive bonding a plug into a large structure like a split fan duct are labor intensive and require expensive fixtures or equipment. A vacuum bag assembly could be constructed around the bond area and the part would be placed in an autoclave for the application of heat and pressure. This method requires an expensive piece of capital equipment, and the use of vacuum bags, particularly for high temperature polyimide materials, are labor intensive and subject to leaking or bag failures.
Alternately, a custom clamping mechanism could be developed in conjunction with a local heating device or the use of a large oven. This approach requires specially designed equipment and is cumbersome to apply on a large structure like a split fan duct.
It would be an advantage to provide a simple, inexpensive and effective way to place a plug in a damaged composite product such as a split fan duct.